package com.wc.blue_bridge_test.base.T63;

import java.util.Scanner;

/**
 * @Author congge
 * @Date 2023/12/28 9:13
 * @description FJ的字符串
 * https://lx.lanqiao.cn/problem.page?gpid=T63
 */
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        StringBuffer[] ans = new StringBuffer[26 + 1];
        ans[1] = new StringBuffer("A");
        for (int i = 2; i <= 26; i++) {
            ans[i] = new StringBuffer();
            ans[i] = ans[i].append(ans[i - 1]).append((char) ('A' + i - 1)).append(ans[i - 1]);
        }
        int n = sc.nextInt();
        System.out.println(ans[n]);
    }
}
